Brush holder



J. H. BURNITE zwar/00a glllllllll Patented Mar. 19, 1935 PATENT OFFICE BRUSH HOLDER vJames H. Burnite, St. Louis, Mo., assigner to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application September 12, 1932, Serial No. 632,692

8 Claims.

vMy invention relates to improvements in movable brush. holders and while the invention is applicable to dynamo electric machines having any'form of movable brush holder, it is particullarly advantageous for use in machines having rush holdersl for vertical face commutators.

In-electric motors for certain kinds of service, such asreirigerating devices and other apparatus for homhold use, it is highly desirable that all noise be reduced to a minimum. In motors having shiftable brush holders it is necessary, to permit easy and free moving of the holder, to provide a clearance between the holder and its support. This clearance permits chattering of the brush holder on its support due to vibration which may be produced by the irregularities of the commutator surface and by the irregularities and misalignments of the operating parts of the brush holder moving mechanism.

One of the objects of my invention is to provide means for reducing the noise caused by the chattering of the brush holder upon its support, while at the same time permitting easy shifting of the holder.

Another object of my invention is to provide means for damping the vibrations of a movable brush holder which is simple in construction and operation and may be economically manufactured and assembled.

Ilo Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawing, showing one embodiment thereof, in which Figure 1 is a cross sectional View of a portion of a single phase motor showing my invention applied to a movable brush holder and in addition thereto, the relationship of the brush holder with the vertical face commutator and the cooperating means for moving the brushes; and Figure 2 is :lo an enlarged view of my novel spring for damping the vibrations of the brush holder.

Referring to the drawing in detail and particularly to Figure 1, which illustrates a well known type of circuit changing apparatus for single phase motors, the end plate l has journaled therein the end of the rotor shaft 2 and is provided with a tubular extension 3 surrounding the shaft and upon which the movable brush holder 4 is supported. The brushes 5 carried by the holder, are biased toward the vertical face of the commutator 6 by means of the springactuated followers '7. The brush holder is actuated into operative relation with the commutator by means of the spring 8 on the shaft, and is moved out of operative relation by means of collar Aio 9 actuated by rods 10 which are connected to the centrifugal mechanism (not shown). In the running position, the commutator is short-circuited by a plurality of short-circuiting plates 11 carried by thecollar 9. Y

In order that the brush holder may be freely slidable on the tubular support, it is necessary to provide a clearance between these twoy members. This clearance, however, permits a chattering of the holder resulting from vibrations transmitted thereto by theadjacent operating parts of the machine, some of the sources of vibration being the irregularities of the commutator surface, slight longitudinal reciprocations of the rotor, and irregularities and misalignments of the brush holder moving mechanism due to machining errors.

In accordance with my invention I decrease the noise caused by the chattering of the brush holder by damping its vibrations by a specially formed spring interposed between and in Contact with the brush holder and its support. The bearing surface of the brush holder sleeve is provided with a circumferential recess or groove 12 into which ts the damping element 13 which, in the form shown, is a strip of spring material circular in general outline but varying from true circular shape as illustrated whereby spaced apart outer surfaces 14 engage the bottom of the recess in the holder, and the inner surfaces of the intermediate portions 15 bear on the support. The thickness of the spring is less than the depth of the recess 12 and it, therefore, functions as a yieldable means resisting relative transverse y movement of the holder and the support. The 3D distribution of contact points is such that the spring does not increase the sliding friction between the surfaces of the holder and the support, and since the pressure of the spring on the support at the contacting points of the surfaces 15, needs to be only very light, the total frictional resistance to the operative movements of the holder is not substantially increased.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a dynamo electric machine provided with a commutator, a brush holder and a brush holder support, means biasing the brush holder to brush operative position, said brush holder engaging the support and being movable thereon to move the brushes into and out of contact with the commutator and being subject to vibrations transmitted thereto from other parts of the machine,

and yieldable means independent of the biasing means for damping said vibrations.

2. In a dynamo electric machine provided with a brush holder support, a brush holder engaging said support and slidable thereon and subject to vibrations transmitted from other parts of the machine, and yieldable means in contact With the brush holder and the support for damping said vibrations.

3. In a dynamo electric machine provided with a brush holder support, a brush holder movable on said support and subject to vibrations transmitted from other parts of the machine, and yieldable means independent of but contacting with the holder and support for resisting relative transverse movement of said brush holder and support.

4. In a dynamo electric machine provided with a brush holder support, a brush holder movable on said support and subject to vibrations transmitted from other parts of the machine, and yieldable means between said brush holder and the support for damping said vibrations, said means comprising an annular spring element having spaced apart portions of its outer surface in contact with the brush holder and spaced apart portions of its inner surface in contact with the support.y

5. In a dynamo electric machine provided With a tubular brush holder support, a brush holder sleeve movable on said support, one of said elements being provided with a recess, and spring means in said recess contacting with the holder and the support.

6. In a dynamo electric machine provided with a tubular brush holder support, a brush holder sleeve movable on said support and provided with a circumferential recess in its bearing surface, and an annular spring element in said recess, said spring being provided with spaced apart portions contacting With the brush holder and with portions intermediate thereof contacting with the support.-

7. In an electric motor of the brush lifting type provided with a cylindrical brush holder support, a brush holder sleeve slidable on said support and subject to Vibrations transmitted from other parts of the machine, and yieldable means for damping said vibrations.

8. In a dynamo electric machine of the type in which the brushes are automatically shifted into and out of contact with the commutator during the cycle of operation of the machine, a commutator, a brush holder support, a brush holder, said brush holder being movable on the support to move the brushes into and out of contact with the commutator and being subject to vibrations transmitted thereto from other parts of the machine, and yieldable means for damping said vibrations.

JAMES H. BURNI'I'E. 

